Relationships between herbicide use intensity, weeds and yield: critical analysis of current methods and results
Relations entre niveau d’usage d’herbicides, flore adventice et rendement : analyse critique des méthodes et synthèse des acquis
Résumé
There is an urgent need to investigate how to manage weeds with fewer or no herbicides in arable farming.
The questions of weed harmfulness, herbicide efficacy, the effects of herbicide use on crop yields, and
the effect on crop production of reducing herbicides have been addressed over the years but results often
appear contradictory. Here, we critically reviewed published studies focusing on the interactions between
herbicide use, weeds and crop yield. We demonstrate that many inconsistencies result from differences
in methodologies and in the conceptual model that links the three items. Our main findings are: (1) The
methods used to assess weed impact on crop production are often inadequate, yet, there is evidence
that, if not compensated by proper combined sets of cultural techniques, herbicide reduction increases
weed infestation ; (2) Reducing herbicide use rarely increases crop yield loss if farmers compensate by
other cultural practices ; (3) Comprehensive cropping-system studies are needed that explicitly include
weeds and disentangle herbicide impacts from the effect of other practices on weeds and on crop
production. We conclude that herbicide use can be reduced without losing crop production if cropping
systems are redesigned by combining agronomic and biodiversity-based levers and accounting for the
production context.
Résumé : Pour comprendre comment gérer les adventices avec peu ou pas d'herbicides en grandes cultures, étudier la nuisibilité des adventices, l'efficacité et les effets des herbicides et de leur réduction sur le rendement est nécessaire. Cette question a été étudiée depuis des années mais les résultats apparaissent souvent contradictoires. Notre article propose une analyse critique des publications scientifiques traitant des relations entre usage d'herbicides, adventices et rendement. Nous démontrons que de nombreuses incohérences résultent de différences méthodologiques et du choix liant ces trois items. Les méthodes utilisées pour analyser la relation adventices-production sont souvent inadéquates ; cependant, il y a des preuves que, sans compensation par des combinaisons adaptées de techniques culturales, la réduction de l’utilisation des herbicides augmente les densités adventices. Des études à l’échelle du système de culture sont indispensables, qui explicitement incluent les adventices et démêlent les effets des herbicides de ceux d'autres pratiques, tant sur les adventices que sur la production. Nous concluons que l'usage d'herbicides peut être réduit sans perte de production si les systèmes de culture sont reconçus en combinant des leviers agronomiques, tenant compte du contexte de production.
Abstract : Relationships between herbicide use intensity, weeds and yield: critical analysis of current methods and results
There is an urgent need to investigate how to manage weeds with fewer or no herbicides in arable farming. The questions of weed harmfulness, herbicide efficacy, the effects of herbicide use on crop yields, and the effect on crop production of reducing herbicides have been addressed over the years but results often appear contradictory. Here, we critically reviewed published studies focusing on the interactions between herbicide use, weeds and crop yield. We demonstrate that many inconsistencies result from differences in methodologies and in the conceptual model that links the three items. Our main findings are: (1) The methods used to assess weed impact on crop production are often inadequate, yet, there is evidence that, if not compensated by proper combined sets of cultural techniques, herbicide reduction increases weed infestation ; (2) Reducing herbicide use rarely increases crop yield loss if farmers compensate by other cultural practices ; (3) Comprehensive cropping-system studies are needed that explicitly include weeds and disentangle herbicide impacts from the effect of other practices on weeds and on crop production. We conclude that herbicide use can be reduced without losing crop production if cropping systems are redesigned by combining agronomic and biodiversity-based levers and accounting for the production context.
Mots clés
Écart de rendement
Compétition
Système de culture
Interaction culture-adventice
weed management.
trophic resource use
weeding
crop loss
interaction culture-adventice
systeme de culture
competition
écart de rendement
perte de rendement
desherbage
herbicide
resource trophique
gestion des adventices weed-crop interference
cropping system
yield gap
Perte de rendement
Désherbage
Herbicide
Resource trophique
Gestion des adventices
Domaines
Sciences de l'environnementOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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